javap(1) Basic Tools javap(1) # [NAME](#NAME) javap - Disassembles one or more class files. # [SYNOPSIS](#SYNOPSIS) ``` javap [options] classfile... ``` *options* The command-line options. See Options. *classfile* One or more classes separated by spaces to be processed for annotations such as DocFooter.class. You can specify a class that can be found in the class path, by its file name or with a URL such as **file:///home/user/myproject/src/DocFooter.class**. # [DESCRIPTION](#DESCRIPTION) The **javap** command disassembles one or more class files. The output depends on the options used. When no options are used, then the **javap** command prints the package, protected and public fields, and methods of the classes passed to it. The **javap** command prints its output to **stdout**. # [OPTIONS](#OPTIONS) -help \--help \-? Prints a help message for the **javap** command. -version Prints release information. -l Prints line and local variable tables. -public Shows only public classes and members. -protected Shows only protected and public classes and members. -private \-p Shows all classes and members. -J*option* Passes the specified option to the JVM. For example: ``` javap -J-version javap -J-Djava.security.manager -J-Djava.security.policy=MyPolicy MyClassName ``` For more information about JVM options, see the command documentation. -s Prints internal type signatures. -sysinfo Shows system information (path, size, date, MD5 hash) of the class being processed. -constants Shows **static final** constants. -c Prints disassembled code, for example, the instructions that comprise the Java bytecodes, for each of the methods in the class. -verbose Prints stack size, number of locals and arguments for methods. -classpath *path* Specifies the path the **javap** command uses to look up classes. Overrides the default or the **CLASSPATH** environment variable when it is set. -bootclasspath *path* Specifies the path from which to load bootstrap classes. By default, the bootstrap classes are the classes that implement the core Java platform located in **jre/lib/rt.jar** and several other JAR files. -extdir *dirs* Overrides the location at which installed extensions are searched for. The default location for extensions is the value of **java.ext.dirs**. # [EXAMPLE](#EXAMPLE) Compile the following **DocFooter** class: ``` import java.awt.*; import java.applet.*; public class DocFooter extends Applet { String date; String email; public void init() { resize(500,100); date = getParameter("LAST_UPDATED"); email = getParameter("EMAIL"); } public void paint(Graphics g) { g.drawString(date + " by ",100, 15); g.drawString(email,290,15); } } ``` The output from the **javap DocFooter.class** command yields the following: ``` Compiled from "DocFooter.java" public class DocFooter extends java.applet.Applet { java.lang.String date; java.lang.String email; public DocFooter(); public void init(); public void paint(java.awt.Graphics); } ``` The output from **javap -c DocFooter.class** command yields the following: ``` Compiled from "DocFooter.java" public class DocFooter extends java.applet.Applet { java.lang.String date; java.lang.String email; public DocFooter(); Code: 0: aload_0 1: invokespecial #1 // Method java/applet/Applet."":()V 4: return public void init(); Code: 0: aload_0 1: sipush 500 4: bipush 100 6: invokevirtual #2 // Method resize:(II)V 9: aload_0 10: aload_0 11: ldc #3 // String LAST_UPDATED 13: invokevirtual #4 // Method getParameter:(Ljava/lang/String;)Ljava/lang/String; 16: putfield #5 // Field date:Ljava/lang/String; 19: aload_0 20: aload_0 21: ldc #6 // String EMAIL 23: invokevirtual #4 // Method getParameter:(Ljava/lang/String;)Ljava/lang/String; 26: putfield #7 // Field email:Ljava/lang/String; 29: return public void paint(java.awt.Graphics); Code: 0: aload_1 1: new #8 // class java/lang/StringBuilder 4: dup 5: invokespecial #9 // Method java/lang/StringBuilder."":()V 8: aload_0 9: getfield #5 // Field date:Ljava/lang/String; 12: invokevirtual #10 // Method java/lang/StringBuilder.append:(Ljava/lang/String;)Ljava/lang/StringBuilder; 15: ldc #11 // String by 17: invokevirtual #10 // Method java/lang/StringBuilder.append:(Ljava/lang/String;)Ljava/lang/StringBuilder; 20: invokevirtual #12 // Method java/lang/StringBuilder.toString:()Ljava/lang/String; 23: bipush 100 25: bipush 15 27: invokevirtual #13 // Method java/awt/Graphics.drawString:(Ljava/lang/String;II)V 30: aload_1 31: aload_0 32: getfield #7 // Field email:Ljava/lang/String; 35: sipush 290 38: bipush 15 40: invokevirtual #13 // Method java/awt/Graphics.drawString:(Ljava/lang/String;II)V 43: return } ``` # [SEE ALSO](#SEE_ALSO) •[java(1)](/man/enterprise-packages/openjdk-8-openj9/java.1) •[javac(1)](/man/enterprise-packages/openjdk-8-openj9/javac.1) •[javadoc(1)](/man/enterprise-packages/openjdk-8-openj9/javadoc.1) •[javah(1)](/man/enterprise-packages/openjdk-8-openj9/javah.1) •[jdb(1)](/man/enterprise-packages/openjdk-8-openj9/jdb.1) •[jdeps(1)](/man/enterprise-packages/openjdk-8-openj9/jdeps.1) 8 August 2014 JDK 8 --- Document: javap(1) from openjdk-8-openj9 0.61.0-r3 (Chainguard OS)